<i>Alcaligenes faecalis kw-A</i> biofilm for denitrification of nitrate-rich effluent

Abstract

<i>Alcaligenes faecalis kw-A</i> selected for possessing good denitrification efficiency was used for biofilm development. The biofilm could be developed on a glass surface within 12 hr when 5%, 1×10⁸ cells/ml was used as inoculum. The microcolonies were seen in 6 hr and glycocalyx in 9 hr stage. At 24 hr the biofilm was developed fully and hence was visualised as dense mass. The biofilm protein content showed 48.5% increase in shake flask than in static condition. The exopoplymer is produced in larger amounts in biofilm as compared to the suspended cells. Also, its amount was more by 43% in the biofilm produced in shake flask condition than in static condition. The biofilm could remove 95% nitrate from nitrate-rich effluent in a bench-scale process in 36 hr. The attached growth technique demonstrated here can be utilised to study the effect of favourable as well as adverse conditions on the denitrification efficiency of a culture. The ultimate application of a denitrifying biofilm would be in attached growth or biofilm reactor.